The agency ordered manufacturers to study higher-than-expected fatality rates in propoxyphene overdoses compared with other painkillers -- and possible toxic effects on the heart in when consumers exceed recommended doses.

However, the FDA rejected a petition from the consumer group Public Citizen calling for phased withdrawal of these products.

In its action, announced during a press briefing on Tuesday, the agency rejected the advice of its own advisory panel, which voted 14-12 for a ban on propoxyphene products because of overdose risk and doubts about their painkilling effectiveness.

Propoxyphene is an opioid painkiller chemically similar to methadone. Some pain specialists, such as Dr. Lloyd Saberski of the Yale-New Haven Hospital in Connecticut, criticize propoxyphene as a weak narcotic with no place on the shelf.

"There is no legitimate medical advantage to keeping propoxyphene available," Saberski said. "You are much better off using small amounts of a potent narcotic; there will be little in the way of side effects."

Dr. Janet Woodcock, director of the FDA's Center for Drug Evaluation and Research, defended propoxyphene as an effective combination treatment option that goes beyond the strength of acetaminophen -- commonly known by the brand name Tylenol -- alone.

"All current pharmacologic options for pain have significant liability," she said in a media briefing. "Given the data currently available to FDA, propoxyphene is an acceptable choice for the treatment of mild to moderate pain when it's taken as directed."

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Propoxyphene-containing analgesics may have fewer adverse effects than other options for mild to moderate pain in older patients when nonsteroidal anti-inflammatory drugs are inappropriate, said Dr. Sharon Hertz, also of the FDA's Center for Drug Evaluation and Research.

She said they don't have the same constipation risk as codeine-containing agents or the confusion and sedation risk of painkillers containing hydrocodone. She also noted that the American Geriatrics Society has discouraged use of NSAIDs in the elderly.

This assessment drew sharp remarks from Dr. Sidney Wolfe, acting president of the consumer advocacy group Public Citizen.

"The agency has decided to allow the continued marketing of a drug with the most patient-unfavorable ratio of risks of any drug I have ever seen," Wolfe said. "We will either appeal this anti-public health decision to the new FDA commissioner or argue in federal court that the decision was arbitrary and capricious."

In its decision, the FDA opted to mitigate the risks of propoxyphene while keeping the option open for patients.

The agency will require manufacturers to provide a medication guide with all prescriptions and refills stressing the importance of taking the drugs as directed to reduce overdose risk.

In addition, Woodcock said there are plans underway with the Medicare and Veterans Administration systems to conduct additional studies, including one that involves the safety and prescribing patterns of propoxyphene among the elderly, specifically with regard to the rates of fatalities and hip fractures.

The FDA will also analyze a review of medical examiners' data in the Substance Abuse and Mental Health Administration's Drug Abuse Warning Network (DAWN).

So far, there's been little data available on overdoses, since intentional overdoses are typically not reported to the FDA, said Dr. Gerald Dal Pan of the agency's Center for Drug Evaluation and Research.

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Over a 35-year period, 91 deaths related to propoxyphene have been reported to the FDA. But most were suicide attempts with multiple drugs, so it's hard to establish a direct causal role for propoxyphene, Dal Pan said.